Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
This invention relates to charging flowable
materials into selected cells of a honeycomb structure and,
more particularly, to methods and related apparatus for
selectively manifolding (i.e. plugging) cells of a honey-
comb structure for the fabrication of filter bodies and
other selectively sealed honeycomb structures.
Honeycomb structures having transverse, cross~
sectional cellular d~nsities of one-tenth to onehundred or
more cells per square centimeter, especially when formed
from ceramic materials, have several uses, such as solid
particulate filter bodies and stationary heat exchangers,
which may require selected cells of the structure to be
closed or blocked by manifolding or other means at one or
both of their ends.
A solid particulate filter body may be fabricated
utilizing a honeycomb structure having a matrix of
intersecting, thin, porous walls which extend across and
between two of its opposing open end faces and form a large
number of adjoining hollow passages or cells which also
extend between and are open at the end faces. To form
a filter, one end of each of the cells is closed, a first
subset of cells being closed at one end face and the
remaining cells at the remaining end face, so that either
may be used as the inlet or outlet end of the filter. A
contaminated fluid is broughtunder pressure to one face
(i.e. the "inlet" face) and enters the filter bodies via
the cells which are open at the inlet face (i.eO the
"inlet" cells). Because the inlet cells are sealed at the
remaining (i.e. "outlet") end face of the body, the
cont~min~ted fluid is forced through the thin, porous
walls into adjoining cells which are sealed at the inlet
face and open at the opposing "outlet" end face of the
filter body (i.e. "outlet" cells). The solid particulate
contaminant in the fluid which is too large to pass through
3~
the porous openings in the walls is left behind and cleansed
fluid exits the outlet face of the filter body through the
outlet cells for use~
Parallel work by applicant, as disclosed in the
European application issued under No. 81302986.5, has
resulted in a most efficient solid particulate filter body
formed from a honeycomb structure in which the cells are
provided in transvexse, cross-sectional densities between
approximately one and one hundred cells per square centi-
meter with transverse, cross-sectional geometries having
no internal angles less than thirty degre~s, such as
squares, rectangles, equilateral and certain other
triangles, circl~s, certain elipses, etc. The cells are
also arranged in mutually parallel rows and/or columns.
Alternate cells at one end face are filled in a checkered
or checkerboard pattern and the remaining alternate cells
are filled at the remaining end face of the structure in a
reversed pattern. Thus formed, either end face of the
filter body may be used as its inlet or outlet face and
each inlet cell shares common walls with only adjoining
outlet cells, and vice versa. Other cellular cross-
sectional geometries and other patterns of sealed cells
may be employed to fabricate effective, although perhaps
less efficient filter bodies than those disclosed by the
a~oresaid applicat~on.
For the mass production of such filters, it is
highly desirable to be able to block selected cell ends as
rapidly and as inexpensively as possible. The previously
referred to European application No. 81302986~5 describes
fabricating filter bodies by plugging the end of each cell
individually with a hand-held, single nozzle, air actuated
sealing gun. The hand plugging of individual cells by
this process is long and tedious and is not suited for the
commercial production of such filters which may have
~2~3~
thousands of cells to be selectively sealed. European
application No. 81302986~5 also postulates the use of a
sealing gun mounting an array of sealant nozzles so that
the plugging mixture may be simultaneously înjected into
a plurality or all of the alternate cells at each end face
of the honeycomb structure. However, a working model of
this device is not known to exist for plugging honeycomb
structures having the higher cell densities referred to.
An alternative approach to manifolding selected
cells at an end face of a honeycomb structure has been
developed by the applicant, in which an open surface of a
honeycomb structure is covered by a mask having a number
of openings extending through it. Plugging material is
charged against the outer surface of the mask and through
its openings into the proximal open ends of cells opposite
the openings. A rigid plate having a plurality of bores
extending through it which are spaced and sized ~o coincide
with the open ends of the selected cells at the end face
of a honeycomb structure when the plate is positioned
against the end face in alignment with its bores opposite
the selected cells is used. Successful use of such an
apparatus is dependent upon the ability to provide honey-
comb structures having end faces conforming to the face
o~ the masking apparatus so as to prevent gaps therebetween
which would allow the sealing material to charge into
adjoining cells and to provide predetermined, undistorted
positioning of the cells at the end face of the honeycomb
structure for accurate registration of the selected cells
with the openings in the mask, again, to prevent possible
charging of sealing material into adjoining cells.
In a related areal U.S. Patent 4,410,591 describes
alternate methods o~ fabricating a multiple flow path body
such as a stationary heat exchanger in which a honeycomb
structure is provided having its cells arranged in columns
across its open end faces, an open end face of a honeycomb
structure is dipped into a flowable resist material and
3~
the resist material remDved from selec~ed columns by cutting
it away together with the common walls of the adjoining cells
in the ~elected column or~ alternatively,~he wallsbetween the
adjoining cells of the selected columns are cut away at
the open end face of the structure before dipping the end
face into the flowable resist material, then the resist
material is blown from the selected columns using compressed
air directed down the selected columns where the adjoining
cell walls have been removed. The end face was therea~ter
dipped into a slurry of cement to form a sealed channel
across each o~ the selected columns. The remaining flowable
resist material was subsequently removed by heating.
Although these methods do not involve charging a permanent
plugging material into cells as the purpose is to create
channels across the ends of cells, sufficient plugging
material could be provided to block the cell e~ds exposed
by the cutting step. As the cross-sectional density
of cells in the honeycomb structure is increased, for
example to improve the efficiency of a filter body, the
tolerances needed ~or the removal of adjoining cell walls
required by these methods tigh~en. The problem is
particularly heightened when the filter bodies are
fabricated from extruded ceramic or ceramic-based honey~
comb structures as the present state of the ceramic
extrusion art cannot provide perectly parallel rows and/
or columns of cells. Also, these methods requir~ the
partial destruction of adjoining cell walls and are
entirely unsui~ed for the fabrication of filter bodies or
other selectively sealed honeycomb structures where the
cells are plugged in a checkered or other possible
alternating cell patterns at the end faces.
3~
SUMMARY OF THE INVENTION
The invention relates to a mask or use in
bulk charging a flowable material into a selected subset of
cells of a honeycomb structure having a pair of opposing
end faces and a matrix of thin walls defining a multiplicity
o~ hollow, open ended cells extending through said s~ructure
between said pair of end faces~ said mask apparatus
comprlslng:
at least one base member adopted to be positioned
across one end face,
a plurality of protruding members extending Erom
each base member in the s~ne direction and in special and
shaped arrangement that permits each protruding member to
register with, be inserted in an open end of one of said
cells, and
means at said one end ~ace for providing open
access to open ends of cells in said selected subset by
said flowab].e material~
The invention further relates to a method of
bulk charging a flowable material into a selected subset
of cells of a honeycomb structure having a pair o~ opposing
end faces and a matrix of thin walls defining a multiplicity
of hollow open ended cells extending through said structure
between said pair of end faces, comprising the steps of
providing a mask apparatus, applying s~id mask apparatus
to an end face and charging said flowable material against
and through said mask apparatus and into said selected
subset of cells, the improvement comprising the steps of.
providing the mask described above and
during said applying step, inserting said each
protruding member into an open end of one of said cells.
~l2~D3C~
It is an object of the invention to provide a
method for selectively bulk charging cells of a honeycomb
structure with a flowable material which is compatible
with any desired pattern of cells selected to be charged.
It is yet another obj~ct of the invention to
minimize the overspill of sealing material when bulk
charging selected cells of a honeycomb structure.
It is yet another object of the invention to
provide a method of selectively manifolding large numbers
of cells of honeycomb structures that is more rapid and
less expen.sive than hand filling individual cell ends.
The invention further relates to a method of
fitting a first member having a plurality of protrusions extending
therefrom to a second member having a honeycomb surface with
a multiplicityof openings extending therethrough, said protrusions
engaging selected ones of said openings when said first member
is fitted to said second member, comprising the steps of:
positioning said first member and said
protrusions against said surface; and
vibrating at least one member until said
protrusions engage said selected openings.
In another embodiment, the invention relates
to a method of fabr.icating a solid particulate filtered body
~omprising the steps of:
2S providing a honeycomb structure having a
multiPlicity oE hollow cells extending through the structure
and through a pair of end faces of the structure, said end
faces being substantially identical and formed by a matrix
o:E porous intersecting walls also extending therebetween and
therethrough;
providing a pair of masks, each mask haviny
a pair of opposing faces, a plurality of openings extending
between and through said opposing faces and a plurality of
protrusions extending from one opposing face;
approximately centering one mask with one
~Za;~3(~
6a
end face; and
vibrating said one mask int~ alignment against
said o~e end face with its opeings exposing a first subset of
cells and its plurality of protrusions engaging an equal
plurality of the remaining cells.
The invention further relates to a combination
comprising:
a honeycomb structure having a pair of opposing
end faces and a multiplicity of cells formed by thin walls
extending through and between said end faces;
a body having a plurality of protrusions extending
therefrom, and being positioned with its protrusions against
one end face of said honeycomb structure;
means for limiting lateral motion of said body
acxoss 'said end face; and
means for vibrating said body with respect to
said one end face.
Further objects and advantages of the invention
will become apparent as the description thereof proceeds.
A summary of the invention and its various
~sp~cts will be found in the appended claims.
D~SCRIPTION OF THE DRAWINGS
The various aspects of the invention are better
understood with reference to the accompanying drawings, in
which:
Figs. l and la depict a solid particulate filter
body fabricated using the inventive methods and apparatus;
Fig. 2 depicts a honeycomb structure and first
mask embodiment;
Fig. 3 depicts in a sectionedl profile view~
the mask embodiment of Fig. 2 fitted to the honeycomb
structure;
Fig. 4 depicts a flowable material being charged
through one of the hollow protrusions of the mask embodiment
of Figs. 2 and 3 into a cell of tha honeycomb structure;
~30~
6b
Fig. 5 depicts a press apparatus for using the
several mask embodiments of ~igs. 2 through 4 and 6 through
7b;
Fig. 6 d~picts a second mask embodiment of the
invention being fitted to an end fac~ of a honeycomb;
Fig. 6a depicts a thin flexible member and
pre~ormed plugs of Fig. 6 in an expanded view;
3~
Fig. 6b is an expanded, sectionea, view of area
6b of Fig. 6 depicting the covering of the open ends of
some of the cells by individual plug members and their
protrusion into the cell ends;
Fig. 6c is an expanded end view of the area 6c
of Fig. 6 showing the arrangement of plug elements in
alternate cells of the honeycomb structure exposing the
remaining cells in a checkered pattern for filling;
Fig. 7 depicts a preferred embodiment of the
invention, an elastic mask, and a honeycomb structure with
which it is used;
Fig. 7a is a view of the downstream face of the
mask embodiment of Fig. 7 along the lines 7a 7a depicting
the relative positioning of some of its protrusions and
lS openings;
Fig. 7b is a cross~sectional profile view along
lines 7b-7b of Figure 7;
Fig. 8 is a perspective, schematic view of the
subject flexible mask and a honeycomb structure with
which it is used;
Fig. ~ is an end face schematic view of the
subject flexible mask of Fig. 1 showing the relative
positioning of some of its adjoining openings and
protrusions;
Fig. 10 is a sectioned view of the subject
flexible mask being fitted to an end face of the honeycomb
structure;
Fig. 11 is a greatly expanded and sectioned
schematic view of the mask fitted to the end face o-f the
honeycomb structure;
Fig. 12 is a schematic view of a solid particulate
filter body formed using the mask and honeycomb structure
of Figs. 1 through 4;
Fig. 12a is a sectioned view of the filtex
body of Fig. 12 along lines 12a-12a;
3 Ql~
Fig. 13a is a sectioned schematic view of a
simple die for casting a flexible mask having protrusions
but no openings;
Fig. 13b is a sectioned schematic view of the
mask formed on the simple die depicted in Fig. 13a having
openings being formed through it;
Fig. 14a is a sectioned schematic view of a
second simple die for forming a flexible mask having
both protrusions and openings, showing a polymer being
loaded into the die;
Fig. 14b depicts the upper surface of the polymer
cast into the second simple die of Fig. 14a being smoothed
to form an outer surface of a flexible mask;
Fig. 14c depicts schematically the curing of
the mask in the second simple die in an oven;
Fig. 14d depicts schematically the flashing being
removed from the lower outer surface of the second simple
die after the mask has been cured;
Fig. 14e depicts a sectioned, schematic, profile
view of the mask produced in the second simple die by the
steps depicted în Figs~ 14a through 14d;
Fig. 14f depicts schematically the undersizing
of the mask with respect to the cells of the honeycomb
structure;
Fig. 15a is an exploded schematic view of a
compound mask forming die appartus;
Fig. l5b is a sectioned profile view of the
compound die apparatus of Fig. 15a in an assembled form;
Fig ~ 16 is a sectioned t schematic view of a
press apparatus for charging a p]astically formable
material such as a plugging cement into a honeycomb
structure using the subject flexible mask; and
Fig. 17 is a schematic sectioned view of a
envisioned press apparatus having a subject flexible mask
incorporated into its exit orifice.
~3~
Fig. 1~ is a schematic view of apparatus for
aligning a mask having protrusions to an end face of a
honeycomb structure;
Fig 19 is a cross-sectional view of the mask
fitted to the end face o the honeycomb structure of
Fig. 18;
Fig. 20 is a schematic view of a preferred
filter body fabricated with the mask and honeycomb
structure of Figs. 18 and 19;
Fig. 21 is a cross-sectional view of the filter
body of Fig. 20 along the lines 21-21 showing the pattern
of cells being plugged at alternate ends;
Fig. 22 depicts patterns of openings and
protrusion locations for the central portions of reverse
masks centered over a cell on the end faces of a honeycomb
structure;
Fig. 23 depicts a view of the central portion
o an end face and the two subsets of cells which are
exposed using identical masks centered on the end face
at one of two locations over a thin wall forming the cells;
Fig. 24 is an exploded view of the central
portion of identical masks showing the two corresponding
locations of their axial centers used with each of the
two axial center locations of the end face represented
in ~ig. 23;
Figs.25 through 27 depict various embodiments
using rigid members extending between a mask and end face
to restrict theix relative lateral or lateral and angulax
movement during the step of vibrating the mask into
alignment.
DETAILED DESCRIPTION OF THE lNV~ ON
A preerred use of each o the embodiments of
the present invention is the fabrication of solid parti-
culate filter bodies as described in ~he aforesaid
European application No. 81302986.5. An exemplary preferred
filter body of that invention i5 depicted in Fig. 1 and
3~
in a cross-sectioned ~iew along the line la-la in Fig. la.
The filter body comprises a honeycomb structure 10 ha~ing
a multiplicity of hollow, open ended passages or cells 11
which typically extend in an essentially mutually parallel
fashion through the structure 10 so as to reduce back
pressure in the filter body being fabricated. The ends
of the cells 11 are open at and form a pair of substantially
identical open outer surfaces at end faces 12 and 13 of the
structure. The cells 11 are themselves formed by a matrix
of intersecting walls 14 which extend between each of
the end faces 12 and 13. For ~ilter body applica~ions,
the walls 14 are porous and continuous across the end
faces 12 and 13 and prefera~ly uniformly thin, although
walls of non-uniform thickness may be used with less
efficiency. A thicker, outex "skin" 15 may be provided
around the cells 11 and thin walls 14 between the end
faces 12 and 13.
Honeycomb structures or solid particulate
filtering and other applications may be formed from a
variety of porous materials including ceramics, glass-
ceramics, glasses, metals, cermets, resins or organic
polymers, papers, or textile fahrics (with or without
fillers, etc.), and various combinations thereof and by
a ~ariety of methods depending upon the material(s)
selected. Honeycomb structures having the necessary
uniformly thin, porous and interconnacted walls for solid
particulate filtering applications are preferably
fabricated from plastically formable and sinterable,
finely div-ded particles and/or short length fibers of
substances that yield a porous, sintered material after
being fired to afect their sintering, especially metallic
powders, ceramics, glass-ceramics, cermets~ and other
ceramic-based mixtures~ An extruded ceramic honeycomb
structure having cordierite as its primary crystal phase,
whi.ch is preferred for moderately high temperature solid
~IZ63 3~
11
particulate filtering applications (1,000 centigrade or
more) due to its low thermal expansion characteristics,
may be provided in the manner described in the afore-
mentioned European application No. 81302986.5. Several
exemplary raw material mixtures are described therein
which yield honeycomb structures with ~hin walls having
various open porosities. The filter body is formed
by plugging, covering or otherwise blocking the ends of a
subset of alternative cells at one end face of the
structure and the rema~ining cells at the remaining ~nd
face of the structure. In Figs. 1 and la, alternate cells
11 of the honeycomb structure 10 have been blocked with
plugs 16 at either end face in a checked or checkerboard
pattern described and claimed in the aforesaid European
application No. 81302986.5. The plugging pattern on the
end face 13 (hidden in Fig. 1) is the reverse of that
depicted on the end face 12. Further inoxmation regarding
the use and operation of the described filter bodies is
provided in the aforesaid ~uropean application No. 81302986.5.
The plugs 16 are selected from a material compatible
with the composition of the honeycomb structure and its
ultimate use as a filter bodyO Where the aforesaid
cordierite structures are used for filtering applications,
cordierite cement plugs 16 are preferably provided or
compatibility. Suitable foaming cordierite cements are
described and claimed in a copending Canadian application
Serial No. 380,875 filed June 30, 1931 and entitled
PATICULATE FILTER AND MATERIAL FOR PRODUCING THE SAME,
which is assigned to the assignee of this application.
A particular composition of the cement preferred for high
sodium ion exhaust gas filtering applica~ions is provided
in the aforesaid European application No. 81302986.50
Nonfoaming cordierite cement compositions may be used
with the porous walled cordierite substrates identified
in the aforesaid European Patent No. 81302g86.5. Alter-
natively, other ceramic cements and other plugging
~3~
12
materials may be used with cordierite or other honeycomb
structures to fabricate filter bodies and other selectively
plugged honeycomb structures using the subject invention
which is hereinafter described in three embodiments,
including a preferred embodiment, in the context of
fabricating the described solid particulate filter bodies.
Fig. 2 depicts a honeycomb structure 10 again
having cells 11 formed by thin walls 14 extending between
end faces 12 and 13 with a first embod~ment mask 20 of the
subject invention. The mask 20 comprises a rigid, essentially
plate-like body 21 having opposing upstream and downstream
faces 22 and 23. The body 21 has a plurality of bores
21a extending axially between its surfaces 22 and 23 each
of which is fitted with a hollow tube 24 which protrudes
like a nipple from the downstream surface 23 of the mask
body 21. The mask 20 is used by positioning its downstream
face 23 against an end face 12 (or 13) of the structure 10
as indicated by the arrows 25, preerably until the down-
stream surface 23 is substantially flush with the end face
12 (or 13) as is depicted in Fig. 3. The tubes 24 are
positioned with respect to one another a_ross the mask
body 21 and sized so as to coincide with and extend into
the ends of selected cells when the mask 20 is fitted to
the end face 12 (or 13~ of the structure 10. A suitably
flowabl~ material (indicated by shading in Fig. 4), such
as one of the aforesaid ceramic plugging cements, which is
charged against the upstream face 22 of the mask 20 under
pressure passes through the tubes 24, as is indicated by
the arrows 26 in Fig. 4, into the ends of the selected
cells into which each tube 24 extends. Desirably, the
outer surface of protruding nipples of tubes 24 taper
inwardly as they extend from the plate-like body 21 so as
to present a smaller transverse cross-sectional area at
their tip for easier registration with the open cell ends.
~3~
13
The base of the nipples may be sufficiently wide so as to
rest on or fit snugly into the ends of the selected cells
11 to prevenk the flowable plugging material from spilling
or oozing over into adjacent cells which are to remain open
or unplugged. The mask 20 may be made from metal components
by assembly, in the manner described, or monolithically by
such methods as casting, or altexnatively, from other
formable or machinable rigid materials. It is also
envisioned that the mask may be formed monolithically
from a flexible or elastic polymer material in a manner
similar to the preferred embodiment subsequently described
herein.
Fig. 5 depicts an exemplary press apparatus 30
which may be used with the first embodiment mask 20 to
charge a plastically formable cement or other viscous
material into selected cell ends o a honeycomb structure.
The apparatus 30 comprises a press head 31 housing a pis~on
32 traveling in a bore 33 which is open at an outer surface
31a of the head 31 and additional frame members 34
supporting a hand-operated screw 35 or other suitable means
for moving the piston 32 in the bore 33. A honeycomb
structure 10 is charged using the mask embodiment 20 and
the subject press apparatus 30 by withdrawing the piston
32 into the chamber 33 forming a cavity between its head
32a and the outer surface 31a of ~he press head 31. The
ceramic cement or other material to be charged in~o the
structure 10 is loaded into the cavity. The honeycomb
structure 10 with fitted mask 20 is applied o~er the bore
33 and against the surface 31a of the press head. Th~
structure 10 and mask 20 are held in position by suitabl~
means such as a bar 36 positioned over the opposing end
face 13 of the structure, which bar is held in position
by suitable means such a threaded bolts 37 extending into
suitably threaded bores 38 in the press head 31. The piston
32 is then advanced towards the mask 20 by means of the
3~
14
screw 35 and presses the material in the cavity through
the tubes 24 into the proximal ends of the cells 11 forming
plugs 16. Plugs 16a have been f~rmed in the rPm~;n;ng
alternate calls of the s~ructure 10 at the opposite end
face 13 in a similar, previous filling operation. The
structure 10 is then removed from the press head and the
plugs 16 and 16a fixed in position by sintering in the case
of the aoresaid cordierite cements or by drying, curing
or other appropriate steps for other plugging materials.
Figs. 6 through 6c depict a second embodiment
of the inven~ion, a multiplicity of preformed plug elements
each of which is inserted into and blocks or covers
the open end of a cell 11 at an end face 12 (or 13) of a
honeycomb structure 10. For convenience, the plugging
elements 40 are preferably prepositioned along elongated
members 41 such as 1exible wires, which are sufficiently
thin ~i.e. of width perpendicular to members 40 smaller
than width of cells) so as to not overlap or substantially
block cells ad~oining those ~emporarily plugged with the
members 40. The flexible members 41 assist considerably
the use of the plug elements 40. The flexibility of the
; members 41 allows some latitude in aligning the plug
elements 4n with distorted arrangements of cells at an
end face. The members 41 also locate the plug elements 40
in the vicinity of the appropriate cell ends during inser-
tion and provide a means for quickly removing the plugs
after the selected cells o the structure have been
charged. Each element 40 has a central body portion 4Oa
which is sufficiently small in diameter so as to be
3Q inserted into an open end of a cell 11. Additionally,
each plug element 40 is provided with a larger head
portion 40b having a diameter greater than the minimum
diameter or width of the open, transverse, cross sectional
areas of the cells. Head portion 40b both covers the cell
ends preventing their charging and prevents the plugs 40
~rom being pushPd complet~ly past the end face into a cell
end during the charging process. To plug alternate cells
11 arranged in rows and columns at an end face 12 of a
honeycomb structure in the aforementioned checkered or
checkerboard pattern, flexible elements 41 each carrying
oneor more plug elements 40 are arranged along alter~ate,
paxallel diagonals of cells at an end ace, as indicated
in Fig. 6c. The plug elements 40 may be inserted into the
cells along the remaining alternate diagonals at the
opposing end face of the structure 10 to achieve the
desired, reversed, checkered or checkerboard plugging
pattern. The flexible members 41 may be provided
sufficiently long so as to o~erlap the sidewalls 14 of the
structure 10 where they may be held in place by suitable
means 42 for the charging methods selected~ For example,
the press apparatus 30 of Fig. 5 may be used by stretch-
fitting an oversized collar, such as an annular, hollow
neoprene ring having an inner circumference sli~htly less
than the outer circumference of the end ace 12, over
the end face 12 and onto the structure sidewalls 15 and
ends of the flexible members 41. Alternatively, an
adjustable clamp, tape or other means may be used to secure
the ends of the flexible members 41 to the sides 15 of
the structure 10. A working model of the masking apparatus
depicted was fabricated by soldering small, copper rivets
at predetermined locations along thin, copper wires.
Although the depicted arrangement of the flexible members
41 along diagonals of cells arranged in rows and columns
is preferred for the fabrication of solid particulate
filter bodies having the preferred checked plugging
pattern depicted in Fig. 1, it is envisioned that other
plugging patterns can be achieved by other spacings of
the plugging elements 40 along the flexible members 41
and other orientations of the members 41 across an open
end ~ace of a honeycomb structure 10.
~n embodiment of the invention which is preferred
for fabricating solid particulate filter bodies or for
otherwise charging 10wable materials into selected cells
~30~
16
of honeycomb structures in which the open ends of the cells
or the arrangement of the cells across the end ace may
be somewhat distorted is an elastic mask described and
claimed in U.S. application Serial No. 283,734, filed
July 15, 1981, and issued as U.S. Patent ~o. 4,411,856
entitled METHOD ~ND APPAR~TUS FO~ HIGH SPEED MANIFOLDING
OF HONEYCOM~ STRUCTURES, which is assigned to the assignee
of this applicakion. An exemplary elastic mask 50 is
depicted in Figs. 7 through 7b together with an exemplary
honeycomb structure 10 with which it is usedO The mask
50 consists of a substantially plate-like body section 51
having a plurality of openings 52 extending substantially
axially therethrough between an upstream face 53 and
downstream face 54. A second plurality of protrusions 55
is also provided extending in a substantially axial
direction from the downstream face 54. The openings 52
and protrusions S5 are spaced wi~h respect to one another
and sized so as to coincide with selected cells 11 when the
mask is fitted to an end face 12 (or 13) of the structure
10. A portion of the openings 52 and pro~rusions 55 are
depicted in Fig. 8a in a view of the downstream face 54
of the mask 50. The openings 52 and protrusions 55 are
alternated with one another along rows and columns
parallel and perpendicular, respectively, to the line 56
o Fig. 7a so as to coincide with alternate cells arranged
in rows and columns, respectively, at the end face 12
(or 13) of the structure ~0. The mask 50 is fitted to th~
end face 12 (or 13) of the struc~ure 10, as indicated by
the arrows 57 in Fig. 7, with the downstream face 54 flush
against the ends of the cells 11, as depicted in Fig. 7b.
Preferably, the protrusions 55 are also elastic and taper
as they extend away from the downstream face 54 from a
cross-sectionaldiameter equal to or greater than a cross-
sectional diameter less than the minimum diameter of the
open, cross-sectional area o the cell ends into which
~2~
17
they protrude. The protrusions 55 assist in aligning the
mask to the end face with its openings opposite the propex
cell ends and temporarily block the cell ends into which
they are inserted preventing ~he plugging or other flowable
material being charged through the mask 50 from entering
those cells. A more detailed description of the fabrication
and use of the mask 50 i5 provided in the aforesaid U.S.
Patent Number 4,411,856. A preferred embodiment for
fitting the mask 50 to an end face of a honeycomb structure
is provided in European Patent No. 8230366.1. A preferred
embodiment ~or fitting the mask 52 and end face of a
honeycomb structure involves sintering the mask with one
end face of the honeycomb structure and then vibrating
the mask into alignment against that end face. With its
openings exposing the first subset of cells and its
plurality of protrusions engaging in equal plurality of
the remaining cells. I a pair of masks is provided, first
one mask is sintered with one end phase of the honeycomb
structure, and then vibrated as men~ioned before, and there-
after the remaining mask is approximately sintered with the
r0maining end ~ace and then is vibrated into alignment
against that remaining end face, with its openings exposing
substantially all of the remaining cells and its protrusions
engaging on equal plurality o the first subset of cells.
It will be appreciated that the described
embodiments are exemplary and that variations and
modifications may be made with respect to each. For
example, although the first embodiment of Figs. 2 through
4 was depicted in Fig. 5 with a press apparatus for
3Q charging a plastically formable or other highly viscousmaterial into selected cell ends, it is envisioned that
the apparatus 20 may be used to charge less viscous
materials such as a plugging cement slurry into selected
cell ends. One way to accomplish this would be to
position the honeycomb structure on its side with its end
faces 12 and 13 in a vertical orientation. The apparatus
:~2~33~
18
~0 is fitted to an end face in the manner described with
its hollow tubes extending into the selected cell ends.
A cement slurry is charged against the upstream face 22
of the mask and injected through the hollow tubes 24 into
the cell ends 11 while the mask 20 is slowly withdrawn
from the end face 12 of the structure 10. The mask 20
would be withdrawn at the rate at about which the slurry
is being deposited into the cell ends. The flow of
slurry would be halted just before the hollow tubes 24 clear
the end face of the structure 10. The structure 10 may
be rolled or vibrated to assure distribution of the
slurry across the cell end. Also, in accordance with
Montierth's teaching in the aforesaid U.S. Patent Number
4,411,856, the plugs 40 of the second embodiment depicted
in Figs. 6 through 6c may be made of a flexible or elastic
material and in a tapered configuration similar to the
protrusions 55 of the mask embodiment of Figs~ 7 through
7b so as to conform to or temporarily seal the cell ends
into which they are inserted.
We shall now describe the embodiments of the
invention shown by Figures 8-17.
Fig. 8 depicts an exemplary mask apparatus 120
and a honeycomb structure 121 with which it is used for
orming a solid particulate filter body in which the cells
127 are sealed in a checkered pattern as indicated in
Fig. 12. The mask 120 consists of a body 122, having a
pair of opposing, typically planar, outer surfaces 123
and 124 (see Figs. 9-11). A number of openings 125
extend through the body 122 between and through the
opposing outer surfaces 123 and 124. A number of
protrusions 126 extend from the downstream face 124 of
the mask 120. The central longitudinal axes of the
openings 125 and pro~rusions 126 are typically normal to
those sur~acesl24 although it is possible and in certain
situations may be desirable to have the openings 125
~1 ~¢D3(~6~
19
incline in a uniform direction with respect to the
surface 124. When the mask 120 is applied to an end
face 128 or 129 of a honeycomb structure 121, the openings
125 allow a sealant or other flowable material to pass
through the mask 120 into those cells 127 of the honeycomb
structure 121 opposite each opening 125. Again, the
protrusions are typically normal to the surface 124 but
may be inclined, if desired or required, with respect to
that outer surface 124.
The honeycomb structure 121 has a large number
of adjoining hollow passages or cells 127 which extend in
a substantially mutually parallel fashion through the
structure between its end faces 128 and 129 (hidden~. The
end faces 128 and 129 typically are substantially square
or perpendicular to the central longitudinal axes of the
cells 127 but may be inclined thereto if desired or required.
In such case the protrusions must be comparably angled so
as to fittably engage the cells and allow the mask to
sit flush to the end face. The cell axes desirably
align substantially with those of the protrusions 126
and openings 125, making fitting of the mask 120 to ~he
end faces 128 and/or 129 easier, and direct the flowable
material passed through the openings 125 directly into
the cells for uniform filling across the cross-sections.
The cells 127 are formed by a matrix of thin, intersecting
walls 130 which extend across and between the end faces
128 and 129. For solid particulate filter bodies, the
walls 130 are also porous and continuous across and
between the end faces 128 and 129. The structure 121 may
also be provided with an outer skin 131 between the end
faces 128 and 129 surrounding the cells 127.
A honeycomb structure 121 may be provided from
any of a variety of suitable materials including metal,
ceramics, glasses, paper, cloth and natural or man-made
3~
organic compounds, as well as combinations thexeof, by
any method suitable for the materials selected. For the
production of solid particulate filter bodies, porous
walled honeycomb structures may be conventionally formed
by extrusion from sinterable mixtures in the manner
described in UOS. Patents 3,913,384 and 4,008,003.
Cordierite compositions preferred for forming substantially
thermostable ceramic honeycomb structures with various
degrees of open porosity, are described in the aforesaid
10 European Patent No. 81302986.5 and in the copending
Canadian application serial No. 380,875. An impervious,
unglazed, sintered manganese-containing ceramic material
has as its major and primary crystal phase a cordierite
crystal structure, has an analytical molar composition of
about 1.7-2.4 RO 1.9-2.4 A12O3 4.5-5.2 SiO2 and is made
of mineral batch composition selected from (a) wholly
raw ceramic material wherein RO comprises~ as mole %
of RO, about 55-95~ MnO and 5-45% MgO, and (b) at least
about 50 wt.% prereacted cordierite material and the
. 20 balance thereof is raw ceramic material, and wherein RO
comprises, as mole % of RO, about 5-40% MnO and 60-95%
MgO. It will be appreciated that a subject mask however,
may be used with honeycomb structures 21 formed from other
materials and/or by other methods.
- 25 The open, transverse cross-sectional areas of
the cells 127 are square and are arranged at the end faces
128 and 129 in mutually parallel rows and mutually parallel
columns which are mutually perpendicular to one another.
It will be appreciated that the rows and columns may not
30 be exactly parallel and perpendicular due to manufacturing
limitations in fabricating the honeycomb structure 121.
The square, cross-sectional geometry and the row and
column arrangement of cells at the end faces depicted in
21
this application are exemplary. A mask 120 may be
fabricated to fit a variety of cellular arrangements
and cellular cross-sectional geome~ries and to provide a
variety of selected cell charging patterns.
The positioning of the openings 125 in and
protrusions 126 on the mask 120 are made with respect to
the cells 127 of the honeycomb structure 121 with which
the mask is used. Each opening 125 is positioned on the
mask to coincide with the open end of a cell to be charged
10 with a filling material through the mask when the mask is
properly positioned over the end face (see Fig. 11).
The openings 125 are suitably sized to expose
the open ends of the selected cell or cells sufficiently
for charging but not so large as to expose part or all
15 of any other cell not to be charged. Larger openings can
be provided to expose several adjacent cells if desired.
Each protrusion 126 is similarly positioned
on the mask to suitably engage and is preferably siæed to
seal a single cell at the end face 128 or 129 over which
20 the mask 120 is fitted. The protrusions 126 are preferably
elastic and taper from a diameter at their base which is
e~ual or larger than, to a diameter at their tip which is
~maller than the minimum cross-sectional diameter of the
open end of cell with which they engage. Cone-topped
25 cylindrical protrusions depicted in Figs. 8-11 are easy
to foxm as are other shapes having a surface of rotation
(i.e. cones, domes, domed cylinders, bullet shapes etc).
The protrusions need not taper along their entire length
although it is desirable that t~e protrusion tip distal to
30 the mask body 122 be tapered to provide some tolerance
during initial registration of the protrusions with the
cell ends. The included angle of taper T between the
protrusion side walls 133 (see Fig. 11~ near the distal
tip of the protrusion 126 should be less ~han 90 degrees
35 and desirably between approximately 10 and 50 degrees.
22
The mask 120 is formed from a flexible material
impermeable to and non-reactive with the sealing material
or other flowable material to be charged through the mask
120. Flexibility allows the mask 120 to conform to
unevenness and some distortions and deformities in the
cellular arrangements at the structure's end faces 128 and
129. This characteristic is significant because in many
cases, notably the ceramic arts~ undistorted and undeformed
honeycomb structures cannot be provided with regularity
10 by conventional manufacturing techniques. This problem
increases with increasing cell densities, increasing end
face dimensions and decreasing structural stiffness during
formation of the structure, and is relatively significant
with respect to a mass fabrica~ion of ceramic-based filter
15 bodies such as the diesel particulate filter embodiment
described in the aforesaid European Patent No. 81302986.5.
Preferably the mask and its protrusions are also elastic.
Such masks are most conveniently formed monolithically
from any of several possible elastomers (i.e., elastic
20 polymers) by casting or injection molding in a manner to
be later described. Elastic masks have been successfully
~ormed ~rom various silicones and urethane although it
is envisioned that other flexible materials including
other elastic pol~mers may be used. Elasticity also allows
25 the mask 120 and protrusions 126 to A~)""~ cellular
spacing distortions at the end faces 128 and 129 and the
tapered protrusions to sealably fit the open ends o
cells 127 withou~ damaging them when the mask 120 is applied.
It is envisioned that the flexible masks will be fabricated
30 from any of several moldable, polymerizable resins including
silicones and urethanes or o~her materials also having a
Durometer Shore A value ranging between approximately 10
and 70 (See ASTM Standard D-1706~ and a Young's (E) Modulus
of approximately 30,000 psi (about 2110 kg./cm.2~ or less,
35 although a Young's Modulus in the range of approximately
500 to 3000 psi (about 35 to 211 kg./cm. ) is preferred for
~3~
~3
ela~tic masks used in fabricating solid particulate filter
bodies from the aforesaid ceramic-based honeycomb structures.
The mask 120 depicted is sized to cover the open
end faces i28 and 129 of the structure 121. Protrusions
126 are provided on the ma$k 120 to fi~ably engage each
cell which is not to be charged with a sealing material
through the mask. It should be appreciated that a protrusion
need not be pxovided for each cell which is not to be charged
at the covered end face and that many of the protrusions 126
on the exemplary mask 120 of Figs. 8 ~hrough 11 could have
been eliminated without detrimental effects. Indeed,
because cells at the periphery of an end face may have partial
or reduced cross-sectional areas which will make fitting a
full-sized protrusion difficult or impossible, it may also
be desirable in some applications to reduce the surface
area o~ the mask to less than that of the end faces allowing
the cells at the periphery of the end face to be charged, or,
if that is unacceptable, to eliminate the protrusions at
the outer edge of the mask. Similarly, in certain
applications it may also ~e desirable to omi~ openings
through certain areas of the mask so as to leave two or more
adjoining cells unplugged.
Care should be taken to account for any shrinkage
which occurs in the fabrication of the mask. If a polymer-
izable resin i5 used, it will typically experience shrinkageat a rate which will differ as the proportions of its
components and the conditions under which it is cured are
varied. Exact sizing of a mask to ~ts honeycomb structure
is preferred as dimensional mismatch will make the fitting
of the mask to an end face more difficult. It was obsexved
that if mask opening/protrusion spacing were excessively
undersized or oversi~ed with respect to the corresponding
cell spacing the elastic protrusions would "knuckle un~er"
while an elastic mask was being pressed against the end
3S ~ace making fitting impossible. Some tolerance to elastic
;~2~3C3~
24
mask undersizing has been obser~ed in applying masks
approximately .125 inches (3 mm.) thick and ha~ing
protrusions about .125 inches (3 mm.~ long and about .07
inches ~about 1.8 mm.~ thick, openings about .086 inches
(about 2mm.) in diameter and a ~oung's Modulus of approxi-
mately 3000 psi (about 211 kg/cm2) or less to honeycomb
structures having cell densities of approximately 100 cells/
sq.in. (about 15.5 cells/s~.cm.) ~hat for very small areas,
approximately one-half inch (1.27 cm) in diameter, about 8
10 to 10% undersizing of the mask could be accommodated; at
diameters of about 4 inches (10.16 cm) about 4% undersizing
of the mask could be accommodated; at a diameter of
approximately 6 inches (15.24 cm) approximately 1% under-
sizing of the mask could be a~cN~ ted~ No tolerance for
elastic mask oversizing was observed although very minor
oversizing (less than 1%) might be ~cc~,alL~Led. It is
believed that approximately 1% undersi~ing over a 6 inch
diameter area could be ac~ ated for other elastic masks
(having a Young's Modulus of up to approximately 10,000 psi
20 (about 703 kg./s~. cm.)). Undersizing of the mask to the
structure is depicted in Fig. 14f with reference to the
centerlines 163 of adjoining protrusions 126 and the
c~nterlines 164 of the cells 127 with which they engage.
Fig. 9 is a view of the outer surface 124 of the
25 mask 120 shown in Fig. 8 and depicts a portion of its
openings 125 and protrusions 126. The openings 125 and
protrusions 126 are alternated with one another along rows
and columns parallel or perpendicular to the line 10-10
50 as to coincide with the rows and columns of cells 127
30 at the end faces 128 and 129. Each opening 125 and
protrusion 126 of the mask 120 in Fig. 9 will be positioned
juxtapose one cell 127 when the mask 120 is applied to
either end face 128 or 129. As the mask 120 has been
fabricated to fit and expose in a checkered pattern the
35 square cells of the honeycomb structure 121, the
~Z~
openings 125 and protrusions 126 are formed in rows mutually
parallel to the line 10a-lOa. The line 10a-lOa bisects
a row of evenly spaced protrusions 126. Rows of evenly
spaced openings 125 and evenly spaced protrusions 126 are
alternated with one another across the mask surface 124
to either side of the row of protrusions bisected by line
10a-lOa. These rows of protrusions 126 and openings 125
will align with the diagonals of the cells 127 when the
mask 120 is fitted to ~he end face 128 or 129. If a
10 plugging material is charged through the openings 125 in
the mask 120, the open ends of the cells 127 in an adjoining
end face 128 or 129 will be filled in a checkered or
checkerboard pattern as is indicated in Figs. 1~ and 12a.
The mask 120 may be hand fitted to an end face
15 128 or 129 of a honeycomb structure in the manner depicted
in Fig. 10. It is suggested that the protrusions 126
ak or near one outer edge of the mask 120 be fitted into
corresponding cells 127 near an edge of the end face. The
mask may be moved laterally for very short distances in a
20 variety of directions across the end face and rotated in
opposing directions to start the engagement of one or more
of the protrusions with appropriate cells in the end face.
Other protrusions 126 are fitted into appropriate corres-
ponding cells in directions radiating from the initially
25 aligned protrusions as indicated by the arrows extencling
acro~s the outer surface 123 of the mask 120 in Fig. 10.
It is helpul to stretch an undersized mask and vibrate it
slightly back and forth across the end face 128 or 129
during this process to align the protrusions 126 with the
3Q appropriate cell ends. Once it is sensed that the
protrusions have aligned with underlying cells, the outer
surface 123 of the mask is pressed down to insert the
aligned protrusions into the cell ends. This process is
continued until the mask 120 is fitted flush acxoss the
35 entire end face 128 or 129 of the structure 121.
3~
26
A solid particulate filter body is formed by
charging a flowable sealing material through the openings
125 in the mask 120 into a subset of alternate cells at
one end face 128 or 129, removing the mask 120, applying
it cr a comparable mask to the remaining end face of the
structure 121 with the openings 125 aligned over the
remaining alternate cells and charging the sealing
material into those cells. The structure and sealing
material may be cured or fired, i appropriate. Foam-type
cordierite ceramic cements, which are compatible with
the aforementioned cordierite structures and chargeable
with the subject mask, are described in the aforesaid
co-pending Canadian application Serial No. 380,875 entitled
PARTICULATE FILTER AND MATBRIAL FOR PRODUCING THE SAME,
filed June 30, 1981, and a preferred composition of this
cement is described in the aforesaid European application
No. 81302986.5. A foamable particulate ceramic cement
capable of forming a sintered cordierite foamed ceramic
mass may consist essentially, by weight, of: 1-40%
cordierite grog, 99-60~ ceramic base material and an
e~fective amount of a foaming agent to effect oaming of
the cement upon firing to produce the foamed ceramic mass.
The base material is a raw ceramic material that has an
analytical molar composition consisting essentially of
abou~ 1.7-2.4 MO 1.2-2.4 A12O3 4 5-5 4 5i2 wherein
MO comprises, as mole ~ of MO, about 0-55% MgO and at leas~
45% MnO. The grog is a ceramic material that has been
previously ~ired and comminuted, and that has an analytical
molar composition consisting essentially of about:
1.7-2.4 RO 1.9-2.4 A12O3 4.5-5O2 SiO2 wherein RO
comprises, as mole % of RO, MnO in an amount of 0% up
to a mole % that is about 20 mole ~ lower than the mole %
of MO that is MnO and the balance is substantially MgO.
It is envisioned that the subject masks may also be used
to charge non-foaming cexamic cements as well as other
~2~3~
27
flowable materials o various viscosities into selected
cells of honeycomb structures for various applications.
A filter ~ody formed rom the structure 1~1 of
Figs. 8 through 11 is depicted in Fi~s. 12 and 12a with
5 alternate cells 127 sealed in a checkered pattern on end
face 128. This pattern is reversed on the end face 129 as
can be seen in part in Fig. 12a, a cross-sectioned view
along a row of the cells in the filter body of Fig. 12
depicting the plugs 132 formed by the sealing material
10 charged through the mask openings 125. Flow of a contam-
inated fluid through the filter is indicated in ~ig. 12a
by arrows 134. The cont~min~ed fluid enters through
the "inlet" cells 127 open at the left ("inlet") end face
128, passes through the thin, porous walls 130, into
15 adjoining "outlet" cells open at the right ("outlet") end
face 129, and in the process leaves the cont~m;nAnts too
large to pass through the walls 130 in the inlet cells open
at end face 128. Additionally the plugs 132 may be formed
with open porosity equal to or less than that of the thin
20 walls 130 and allow some fluid flow therethrough which will
not impair the operation of the filter body. Operation of
the filter is described in more detail in the aforesaid
European application No. 81302986.5.
A second aspect of the in~ention is die apparatus
25 and methods for using the same to fabricate a flexible or
elastic mask similar to that depicted in Figs. 8 through 11.
first mask forming apparatus is depicted in cross-section
in Fig. 13a and consists of a mold 140 having a mask forming
outer surface 141, typically planar, and a multiplicity of
30 bores 142 extending through the mask forming surface 141
and mold 140 in directions essentially normal to the mask
forming surface 141. A cavity 144 in ~ich the mask body
is formed is defined by a ridge 143 which extends outwardly
from the mask forming surface 141. The bores 142 foxm the
35 protrusions 126 of the mask and axe desirably tapered
inwardly as they extend away from ~he mask forming
2~
surface 141, preferably at an included angle bet~en
approximately 10 and 50 degrees. After being cast in a
manner to be subsequently described, the mask is removed
from the mold 140 and openings 125 made through the body of
the mask 120 at selected locations among the protrusions
126 as indicated in Fig. 13b. The openings 125 may be made
by any suitable means such as but not limited to boring,
cutting, drilling (depicted), burning and melting. If
formed from anelas~ic polymer, the mask may be chilled to
make the operation easier to perform. In the preferred
embodiment, the openings 125 are also essentially normal to
the outer downstream surface 124 of the mask 120 from
which the protrusions 126 extend.
Fig. l~a depicts a cross-sectioned profile view a
second mask forming apparatus. Like the first apparatus of
Fig. 13a, the second apparatus of Fig. 14a consists of a
mold 150 having a plurality of tapered bores 152, a mask
forming surface 151, and a ridge 153 which forms with the
mask forming surface 151 a cavity 154 within which the body
of the mask is formed. The second apparatus further includes
a plurality of means 155, such as pins, for forming an equal
plurality of openings through the mask. It is preferred
that the tops of the means 155 form a common plane with the
top of the ridge 153 to assist in forming a flat outer
surface on the mask, as will be subsequently described.
A mask 120 formed within the apparatus of Fig. 14a
is depicted in cross-section in Fig. 14e and has a pair of
opposing outer surfaces 123 and 124, a first plurality of
openings 125 extending through and between the outer surfaces
123 and 124, and a second multiplicity of protrusions 126
extending from the outer surface 124. Again, the
protrusions 126 are preferably tapered downward at an
included angle of between about 10 and 50 degrees and ~he
protrusions 126 and the openings 125 extend essentially
normally from the outer surface 124.
~L~63 3~
29
Simple working models of die apparatus corres-
ponding to those depicted in Figs. 13a and 14a through 14d
can be formed from transverse cross-sections of khe honey-
comb structures with which the masks are to be used. To
form the die of Fig. 13a, the cells of a honeycomb section
are filled with an easily removed solid material such as
wax and affixed to a supporting plate using wax or a suit-
able adhesive. The wax or other solid material is removed
from selected cells in which protrusions of the mask will
10 be ~ormed. The outer perimeter of th sectioned structure
is then surrounded with a collar to form ridge 143 and a
selected polymer is cast in the mold thus formed. A die
apparatus similar to that depicted in Figs. 14a through
14d may be formea by the additional insertion of pins into
15 selected cells of the sec~ioned structure. A Conap, Inc. No.
TU-65 urethane was mixed accordincJ ~o directions and cast
in such an apparatus to establish the feasibility of the
casting processes. After a room temperature cure for about
18 hours, the solidified mask was removed from the die and
20 oven heated at about 200 Fahrenheit (93 Centigrade) for
about 16 hours to complete curing. Preferably, however,
the die apparatus is fabricated from a ri~id, machinable
material such as metal ~or precise dimensioning of the
formed mask. It will further be appreciated that the die
25 apparatus of Figs. 13a and 14a through 14d can be constructed
in two pieces consisting of a flat plate ha~ing a mask
forming surface~141 or 151 with, in the latter case, openings
forming means 155 protruding therefrom and bores 142 or 152
extending therefrom and therethrough and a second plate
30 having a center cutout which is attached to the first
plate 140 or 150 to provide the ridge 143 or 153 forming
the cavity 144 or 154.
A mask is formed in the mold 150 in the manner
depicted in Figs. 14a through 14d. The mold 150 is cl~aned
35 with a suitable agent such as acetone or xylene prior to
33~
forming each mask. After cleaning the inner surfaces of
the mask forming cavity 154 and bores 152 are coated with
a suitable releasing a~ent, such as a 2001 ratio by weight
solution of methylene chloride and ~ohnsonTM Paste Wax.
A suitable polymerizable resin ("polymer'!) is mixed and
de-aired by an appropriate device such as a vacuum chamber.
A mass of mixed and de-aired polymer 156 is applied to top
of the mold 150 and is worked into the cavity 154 and bores
152 with a suitable tool 157 such as a spatula or putty
10 knife. The mold 150 may be mounted on a vibrator platform
158 and/or a vacuum souxce 159 may be applied to the ends
of the bores 152 opposite the mask forming surface 151 in
order to work the polymer into the bores 152 and recesses
of the cavity 154. Other devices such as ultrasound sources
15 (not depicted) may be employed in working the pol~er into
the cavity 154 and bores 152. The surface of the polymer
is leveled with the upper surfaces of the ridge 153 and
opening forming means 155 with the tool 157. The extrusion
of the pol~ner material through all of the openings of the
20 bores 152 at the bottom surface 1~1 o~ the mold 150
indicates that the cavity 154 and bores 152 are filled.
The tops of the means 155 then are scraped clean with a
sharp edge 160 such as a razor as depicted in Fig. 14b,
leaving a smooth outer ~ace on the molded polymer. The
25 polymer is then cured in a manner appropriate for the
materials selected. The curing of many polymers may be
accelerated by baking as is depicted in Fig. 14c. After
baking, the mold 150 and cured polymer are removed from the
oven and are allowed to cool. Once the mold 150 is
30 sufficiently cooled to be handled, the polymer extruded
through the bottom of ~he bores 154 and beyond the bottom
surface 161 of the mold 150 are removed by suitable means
162 such as a razor blade or scraper as indicated in Fig.
14d. The cured polymer is then pulled from the mold and
3S trimmed to an appropriate size, if required. Except for
~3~
31
the cleaning of the pin tops (Fig. 14b), the same steps
are followed in casting a mask in the mold 140 (Fig. 13a).
Again, openings must be formed through the mask after its
removal from the mold 140 (Fig. 13b).
Yet another apparatus, an envisioned compound die
for forming a mask, is depicted in an exploded view in
Fig. 15a and in a sectioned profile view in Fig. 15b, and
consists of a first die piece 165 having means 166 to form
the plurality of openings in the subject mask, a second
10 die piece 167 for forming the flexible protrusions extending
from one face of the mask and a third die piece 168
positioned between the die pieces 165 and 167 for stripping
the subject mask from the die ~fter being formed. This
compound die apparatus allows faster and easier mask
15 fabrication than either of the die apparatus depicted in
Figs. 13a and 14a through 14d. The first die piece 165
has an essentially planar bottom outer surface 169 ~hidden)
from which extends a plurality of means 166 such as pins
or tubes for forming the openings 125 in the mask 120
20 (see Figs. 8 through 11). The second die piece 167 has
an upper outer surface 170 designed to contactably mate
with the ends of the means 166. For ease of use it is
sug~ested that the ends of the means 166 be flat and form
a common plane and that the outer surface 170 of the
25 second die piece 167 also be planar. The second die piece
167 is further provided with a plurality of bores 171
extending therethrough from the outer surface 170. The
walls of the bores 171, which form the protrusions 126
of the mask 120 (Figs. 8 through 11), extend normally away
30 from the outer surface 170 for a short distance and then
taper inwardly, suggestedly at an included angle of between
approximately 10 and 50 degrees as they extend away from
the outer surface 170. The third die piece 168 is
essentially planar and is positioned within a ca~ity 172
35 formed between the first and second die pieces 165 and 1~7,
~3~
32
respectively, when the opening forming means 166 are
positioned against the second piece outer surface 170 ~see
Fig. 15b). The third die piece 168 is provided with a
second plurality of bores 173 equal to the number of means
166 which are positioned and sized so as to allow the third
die piece 168 to be slid along the means 166 and posi~ioned
against the surface 169 of the first die piece 165 with the
means 166 extending completely through and protruding from
lower surface 174 of the third die piece 168. The
10 tolerances between the plurality of bores 173 and means 166
should also be suficiently tight to prevent the intrusion
o~ polymer and the formation of flash during the fabrication
of the mask. However, if flash is formed it may be removed
by suitable means such as water jetting or burnishing. The
15 mask is formed between the lower surface 174 of the third
die piece 168 and upper surface 170 of the second die
piece 167.
A mask may be cast in the third die apparatus in a
manner similar to that used with the first two die
20 embodiments. The die pieces 165, 167 and 168 are cleaned
and a removal agent applied to the mask forming surfaces.
A suitable polymer is mixed, de-aired and applied to the
upper face 170 of the second die piece 167 and is worked
into the bores 171. The second piece 167 may be formed
25 with a ridge 175 to contain the polymer during this process.
The mated first and third die pieces 165 and 168 are
pressed against the second die upper surface 170 and held
in place by suitable means 176 such as clamps (depicted)
or screws or nuts and bolts during the curing of the polymer.
30 If the peripheral ridge 175 is provided, it should be low
enough so ~hat one or more narrow gaps 177 are formed
around the cavity 172 through which excess polymer material
may be squeezed (see Fig. 15b). The third die piece 168
is held against the first die piece 165 by the polymer
35 between the piece 168 and the second die piece 1~7. After
curing, polymer extruded through the tapered bores 171 is
3~
33
again removed by a suitable ~ool such as a razor kni~e
(see Fig. 14d). The means 176 used to hold ~he three die
pieces together are removed and the second die piece 167
removed from t~e first and third die pieces 165 and 168.
Frictional forces will hold the mask 120 to the openin~
forming means 166 extending through the mask ~orming lower
surface 174 of the third die piece 168. This mask forming
lowersurface 174 eliminates the separate upper mask surface
forming step required in the first ~wo die embodiments (see
particularly Figs. 14a and 14b). The mask 120 thus formed
within the cavity 172 and tapered bores 171 may be stripped
from the opening forming means 166 by sliding the third
die piece 168 along the means 166 away from the first die
piece 165. If desired or necessary, the formed mask may
be trimmed to a suitable shape for use.
Comparable die pieces may also be used for
injec-tion molding of the mask. In an injection molding
apparatus, means are provided for in~ecting the polymer or
other flowable material into the cavity, such as through the
g~p(s) 177.
Sintered honeycomb structures with which the
described mask have been used, typically experience
shrinkage during their drying and sintering cycles which
vary with compositional and drying/curing schedule
variations. By varying polymer mixtures and/or curing
schedules, the shrinkage and thus the relative dimensions
of the flexible mask fabricated may also be controllably
varied. In this way, a single die appaxatus may be used
to fabricate different masks accommodatin~ honeycomb
3a structures experiencing-siightly different shrinkages.
Again, exact sizing of the mask to the structure is
desired but to the extent that that goal cannot be achieved
slight undersizing is preerr~d to oversizing. Several
silicone ormulations have been successfully cast using a
35 die apparatus similar to that depicted in Figs. 14a
~26~3~
34
through 14d formed from machined ~rass plates incorporating
steel, opening f~rming pins. In each case, the pol~mer
components were mixed,de-aired with an approximately 28 inch
(71.1 cm.~ mercury vacuum for about 20 minutes, applied to
the die apparatus and hea-ted for about 8 to 10 minutes at
about240 to 260 Centigrade to accelerate curing. A~ter
cooling and remo~ing from the die apparatus, some masks
were subjected to an additional post-curing cycle in which
each was again heated at approximately 230 to 250 Centi-
grade for about 16 hours. In each such case, post-curing
yielded additional shrinkage. Silicone mixtures which have
been successfully cast and their ohserved linear shrinkage
from original die ~ ions under the a~oresaid oven curingand
where indica~ed, post-curing schedules are as follows (all
~ are by volu~e except where otherwise indicated2.
ADDI TIONAL TOTAL
CU~E POST-CURE SHRINK-
20 SHRINKAGE SHRINKAGE AGE 9~
POLYMER ~ (APPROX. ) ~ (APPROX. ) (APPROX. )
1. Dow Corning Q3-9595*
silicone resin (50
A component mixed
with 50% B component) 3. 0-3. 3 0.5-0.8 3. 8-4.0
25 2. Dow Corning Q3-9590*
silicone resin (50% A
component mixed with
50% B component~ 2.3-2.61. 4-1.7 about 4.0
3. Dow Corning Q3-9595*
(50% component A mixed
with 50 % component B2
mixed with additional
10% (by weight) Dow
Corning X3-6596A* sili-
cone resin (.A compo-
nent only) 2.3~3.00.8~1.0 3.8-4.0
4. Dow Corning X3-9592*
(50% ;~ component mixed
with 50% B component) 2. 5-2. 80.7-1.0 3.2-3.5
*TradOEk
~3qO ~
ADDITION,A,L TOTAL
CVRE P(:)ST-CURE 5EIRINK--
INRAt~E SII E?<INKA(7E AGE ~6
POLYMER 9d (:APPROX. ~ % ~:APPROX . ~ (APPROX . )
5. 50% (by weight) Dow
Cornin~ Q3-9595* B com-
ponent silicone resin
mixed with 50% (hy
weight) Dow Corning
X3-6596*A component
silicone resin 2.8-3.0 about 1~0 3.8~4.0
6. Dow Corning X3-6596*
silicone resin (50% A
component mixed 50% B
componentl 1.9-2.1 0.7-0.9 2.7-3.0
7. 25% (bv weight)Dow
Corning Q3-9590*sili-
cone resin (50% A
component mixed with
50~ B componen~) mix-
ed with 75~ (by
weight~ Dow Corning
X3-6596* silicone resin
(50% A component mixed
with 50% B component] 2.2-2.4 1.0-1.2 3.5-3.7
8. 25~ Dow ~orning
Q3-9590*silicone
resin (50% A componen~
mixed with 50% B com-
ponent) mixed with
75% Dow Corning X3-6596*
silicone resin (50% A
component mixed with
50% B component) 2.5-3.0
9. 90~ Dow Corning Q3-9595*
silicone resin (50
component mixed with
50% B componentl mixed
with 10% Dow Coxning
3X-6596*A component
silicone resin 2.5-3.0
10. Dow Corning No. 732*
silicone resin (50%
A component mixed with
50~ B componentl 1.8
*Trademark
~3~
36
ADDITIONAL TOTAL
CURE POSTCURE SHRINK-
SHRINKA~E SHRINKAeE A~E %
POLYMER %-(~PPROX.~ ~APP~OX.) (APPROX.
11. Dow Corning No. 734*
silicone resin (50%
A component mixed with
50% B component) 1.8
Silicone oils have also been added to silicone resins to
obtain even greater shrinkages. In each case, the oil was
mixed into a mixed silïcone resin, de-aired, cast and heated
in a mold through the a~oresaid curing schedule (230 to 260
Centigrade ~or 8 to 10 minu~es~ but was subjected to a post-
cure baking at about 230 Centigrade ~or only about 4 hoursO
The mixtures examined and their cure, additional post-cure
and total shrinkages are as ~ollows (all % are again by
volume unless otherwise indicated).
ADDITIONAL TOTAL
CIJRE POST-~URE SHRINK-
SEIRINKAGE SH~INKAGE AGE ~
POLYMER~ (APPROX. ) % (APPROX. ~(APPROX. )
12. 82.5% (by weiyht~Dow
Co~ning X3-6596* sil-
icone resin (50% A
component mixed wi~h
50~ B component~ mixed
with 17. 5% Dow 200 Sil-
icone Oil 20CS*2.6-2.8 1.8-2.0 4.4-4.6
13. 90~ (by weight) Dow
Corniny X3-6596* sil-
icone resin (50~ A
component mixed with
50% B component)
mixed with 10~ Dow 200
Silicone Oil 500CS*2.4-2.7 0.6-0.8 3.1-3.5
Other ratios and curing schedules should yield a range of
shrinkages. At least one silicone resin, Dow Corning 184*,
could not be cast on the aforesaid ~old apparently due to in-
teraction with the brass~ Adverse reactions may be encountered
with other die material and polymer mixes.
*Trademark
31~
Yet another aspect of the in~ention are mekhods and
appaxatus for manifolding selected cells o~ a honeycomb
structure as ~ould be done during the abrication of solid
particulate filter bodies, using the flexible, elastic
masks heretofore described. An exemplary press apparatus
180 is depicted in cross-section in ~ig. 16. A ~lexible
mask 120 and honeyco~b structure 121 are pro~ided in the
manner pre~iously described. The mask 120 has been applied
to an end ~ace 128 of the honeycomb structure 121 with its
protrusions 126 and openings 125 aligned with the ends of
alternate cells 127 at the end face 128. Slight under-
sizin~ o~ the mask 120 will provide mechanical self-
locking of it to the structure 121. Moreover, it is
suggested that a ~lexible tubular collar 181 of a suitable
material such as neoprene be stretch ~itted over the
peripheral edges o~ the mask 120 and outer sidewall 131
of the structure 121 adjoining the end ~ace 12B to assist
in holding the mask 120 to the structure 121 and in sealing
the structure 121 over an oriice 183 on the upper face 194
o~ a press head 186. An adjustable, flexible clamp 182 is
provided around the collar 181 so as to better secure it
to the mask 170 and structure 121. The press apparatus 180
comprises ~he press head 186 supported bv a frame 188. The
head 186 is equipped with a piston 184 slidably mounted
in a bore 185 for charging a cement mixture through the
orifice 183 over which a honeycomb structure 121 is
secured. Prior to charging, the piston 184 is backed
away su~ficiently ~rom face 194 to form a chamber above
the piston head which is loaded through the orifice 183
with a suitable amount of a ceramic cement such as the
~oam-type cements previously referred to. The mask 120
and structure 121 mounting the collar 181 and clamp 182
are then placed over the orifice 183 and held in place by
suitable ~eans such as a bar 189 placed across the
remaining end face 129 of the structure 121 and held into
place by suitable means such as bolts 190 extending
through the bar and into suitably threaded bores 191 o~
the press head 186. The piston 184 is then advanced
3~
38
towards the exit ori~ice 183 by ~eans of a hand-operated
screw 187 or other suitable ~eans and, in the process,
presses the cement mass ~ove the piston 184, against the
mask 120, and through its openin~s 125 into the proximal
open ends of the cells 127 juxtaposed to the openings 125
forming cement plugs 192. During this step, the flexible
collar 181 also seals the circum~erential edge o~ the
orifice 183 preventing the cement *rom being foxced out
past the end ~ace 128~ Similar plugs 193 have already
been formed in the ends o~ the re~aining alterna~e cells
127 proximal the end ~ace 129 in a previous ~illing. The
structure 121 may then be removed ~rom the press apparatus
180 and the flexible collar 181 and mask 120 removed from
the structure 121, which is ready ~or ~iring to sinter
plugs 192 and 193 and structure 121, if appropriate.
Parallel work by the applicant has resulted in a
double headed cement press for simultaneously ~illing
both ends of a honeycomb structure using a pair of the
subject masks. Where a pair of masks are used, they may
be held in place during handling of the honeycomb structure
before its insertion into the press by providing under~
sized masks or by temporarily securing the masks to the
~nd ~aces of the honeycomb structure with a mild adhesive
which will allow their easy removal after charging.
It is fur~her envisioned that the subject mask 120
may be ~itted across the feed orifice 201 of a filling
device such as a cement press having a press head 200 as
depicted schematically in Fig. 17 so as to ~eed a *low-
able material, in this embodiment a plastically ~ormable
cement, into a honeycomb structure fitted to the filling
device's ~lexible mask 120. The ~ask 120 is secured to
the press head 200 in a suitable collar 202 by an annular
plate 203 or other suitable mean~. The collar 202 is
secured across the ~eed orifice 201 again by suitable
means such as threading 204 or ~asteners (not depictedl~
The s~ructure 121 is brought to the mask and ~i~ted
3~
39
against its e~posed protrusions 126. Cement (shading~
is fed into a cavity 206 foL~ed in the press head 200
between a piston 205 and the upstrea~ face 123 of the
mask 120 through appropriate means such as feed tubes
207. The piston 205 is advanced as indicated by arrow
208 and forces the ce~ent against the mask 120 and
through its openings 125 into the open ends of the
opposing subset of cells 127. I~t is further envisioned
~or ~abrication of solid particulate filter bodies and
other honeycomb structures manifolded at both their end
~aces that a second press head similar to the head 200
depicted be provided with an appropriate mask 120 for
simultaneous charging of both end faces of the structure.
A preferred embodiment of a method for automatically
fitting a subject flexible mask to a honeycomb structure
~ill be described with reference to ~igures 18-27.
According to the invention, a~ter being placed on
the end face 312, as indicated by the arrows 322, the
~ask 311 is xapidly vibrated about and around the center
of the end face 312 until it moves into lateral and angular
alignment with its protrusions 315 enga~ing the cells 316.
In Fig. 18, the honeycomb structure 310 has been positioned
on the surface 323 o~ a mechanical vibration source.
Preferably the surace 323 imparts a rotational vibrating
motion. A suitable device has been constructed by mounting
to the base of a commercially available rotary vibratory
parts ~eeder in place of its feeder bowl, a flat plate.
The surface of the plate ro-tates back and forth through a
short arc about its center, the motion being sharp in one
direction and relatively slower in the return direction.
The surface experiences no net lateral or rotational
movement but a suf~iciently light object (such as a
structure and mask~ placed upon its sur~ace will rotate,
and, i~ placed o~f~center rom the rotational axis, orbit
in short hops about the rotational axis. Desirably, means
are also provided to control the amplitude of the vibra-
4Q
tory motion generated and thereby control the rotationalspeed of the mask and/or structure. Yibration amplitude
o~ the pre~iously re~erred to parts feeder was controlled
by means of a rheostat. A Yibrational frequency of about
60 hertz has been used to seat the described masks but it
is envisioned that a wide range o~ frequencies, approxi-
mately 30 to 200 hertæ or more, may bP employed
success~ully in seating the described flexible masks.
Other frequency ran~es may be found desirable for other
applications of the invention. Rotakional vibration is
trans~itted ~rom the surface 323 to the mask 311 resting
on the end face 312 through the structure 310 which is
preferably centered over the axis of rotation o~ the
surface to minimize lateral movement of structure 310
and mask 311. Alternatively, it is en~isioned that the
mask 311 mav be directly contacted by a vibration source
and vibrated into alignment. Also it is envisioned that
the positions of the mask 311 and structure 310 may be
reversed with the ~ask 311 on the surface 319, its
protrusions extending upwards. Although random, linear
or orbital (planar, orbitting movement without rotation
of the vibrating plane) vibration may be usedr rotational
vibration in the plane between the end face 31~ and mask
311 is preferred as it causes the mask 311 to rotate
steadily around the end face 312 facilitating angular
as well as lateral alignment. Rotation of the mask with
respect to the end face may have to be otherwise
accomplished if randon, linear or orbital vibration is
used. PreEerably, the structure 310 is temporarily held
in position on the surface 319 to better transmit the
~ibrational motion from the surface 319 to the mask 311.
The structure may be held by any of several suitable
methods including the use o~ a re~ovable temporary
adhesive, clamps, or a pair o~ pins or the like
extending through the plat~orm surface and into a pair
of the structure's cell ends sitting on the surface 319.
3~
~1
A collar 324 has heen attached to the side walls 318 of
the structure 310 and extends above the end face 312 50
as to confine the mask 311 within the collar. In this
manner, the lateral moY~ment o the axial center of ~he
mask 311 across the end face 312 is limited to a s~all
predetermined area about the axial center of the end
face 312. The faces 320 and 321 o~ the mask 311 can be
appropriately si2ed to define the size of the area about
the axial center of the end face 312 in which axial
center of the mask 311 is con~ined. It is envisioned
that in some configurations, proper alignment of a mask
311 and end face 312 or 313 may be achieved simply through
orbital vibration without the use of a constraint ~uch as
the collar 324. other means of lLmiting the lateral
movement bet~een the mask and honeycomb structure will be
described subsequently.
To fabricate the solid particulate filter body 325,
the mask 311 is aligned over the end face 312 with its
openings exposing a flrst subset of cells. A similar mask
(not depicted~ is aligned over the end face 313 of the
honeycomb structure 310 with its openings exposing a
substantially different subset of cells. The exposed
cells 316 are plugged with a suitable material passed
through the openings 314 of both masks. It will be
appreciated, of course, that each end face may be covered
with a mask and filled in sequence or that both end faces
may first be covered and then filled simultaneously or
in sequence. The filter body 325 of Fiys. 20 and 21
has been foxmed from the structure 310 of Figs. 18 and
19 by plugging the cells 316 in a desired checkered
pattern at the end faces 312 and 313. The pattern of
plugged cells on end face 312, depicted in Fig. 2C, is
reversed on the hidden end ~ace 313 as can be ascertained
in Fig. 21 where the filter body 325 has been sectioned
along a line (row or columnl of cells 316 re~ealing the
plugs 326 formed in al~ernating cell ends along the line.
3~
42
To achie~e the checkered plug~ing pattern e~hihited by
the filter body 325 in ~i~s. 20 and 21, the openings
314 o~ the mask 311 u~ed with th~ structure 310 ~ere
arranged in mutually parallel rows and columns across
the mask surface with pxotrusions 315 located there-
between to engage all or substantially all of the
remaining alternate cells at the end face~ It will be
appreciated that for various applicat~ons other than
Eiltering, it may be desirable to plug some cells at
both their ends, to leave some cells unplugged or both.
Also, plugging patterns other than the depicted checkered
arrangement may be employed. In each case, however,
the plugging pattern on each end face of the filter body
will be substantially, if not, identically, the reverse
of that at the remaining end faceO Typical fluid flow
through the filter body 325 is indicated by the arrows 32~.
The aligning of bodies, such as ~lexible ~asks to
honeycomb surfaces such as the described end ~aces, may
be automated. For the fabrication o~ solid particula-te
filter bodies, auto~ation is simpli~ied by using particu-
lar honeycomb structures and masks to assure proper cell
exposure through the masks at the two end faces.
A first embodiment comprises in part a honeycomb
struc~ure such as the structure 310 of Figs. 18 and 19
with the axial centers of its end ~aces located at or
approximately at the center of the transverse cross-
sectional area of one of its square cells. A pair of
so-called "reverse" masks is also provided~ The openings
314 of each of the reverse masks will expose completely
or substantially di~ferent subsets of cells ~hen each
of the masks is identically located on an end face of
this honeycomb structure. Fig. ~2 depicts the area of
an end ~ace 312 or 313, about its central cell 329 and
adjoining cells 316 o~ the structure 310 arranged as
they are arranged across the end faces 312 ~nd 313 in rows
and columns. The cells 316 are divided into alternate
3~
43
subsets which are identified by "X's" and "o's" and yield
the desired checkered pattern o~ plugged cells illustrated
in Figs. 20 and 21. ~he l'X's" and "o's" also represent the
locations of openin~s and possible protrusions, respectively in
~ne of the reverse masks and the con~erse on the other
reverse mask of the pair. Again, a protrusion typically
but not necessarily isloca~ed opposite each cell end not
to be filled. Each reverse mask is fitted to an end face
by approximately centering the mask against the end face
(i.e. positioning the mask with its axial center within
the confines of the central cell 329 or sufficiently near
to the central cell so that the axial center of the mask
is prevented from aligning over any cell other than the
central cell 329 due to the thickness of the protrusions)
and vibrating the mask into alignment. Again, means such
as the collar 324 (see Fig. 18~ are preferably provided to
assure that the axial center of the mask aligns over the
center cell 329. This area within which the axial center
of the mask is initially posi~ioned and later con~ined
during alignment is centered at the center of the central
cell 329, andr in the case o~ the uniformly sized cells
316 depicted, can have a maximum diameter at least as great
as a cell pitch (i.e. the distance between the centers o
adjoining cells in a row or column), and may have a some-
what greater diameter, depending upon the diameters of
the protrusions at their tips, but in no event will the
maximum diameter be as great as twice the magnitude of
a cell pitch as this would allow the mask to center over
a cell other than the central cell 329. Each o the
reverse masks will align opposite the center cell 329 in
one of four possible angular orientations separated by
90. On the mask having its protrusion locations
represented by "X's 1l, apart from the protrusion which
may be proYided to engage the central cell 329, the four
protrusion locations closest to the axial center of thP
mask will always align in those four cells lying along the
;33~
44
diagonal lines at b, c, and d and the mask will al~ays
expose the same subset of cells indicated by the "o's".
Similarly, the our protrusion locations closest to the
axial center of the remaining re~erse mask (represented
in Fig. 22 by the "O's" about the central cell 329~ will
always align only in the cells lying along the vertical
and horizontal lines e, f, g and h and expose only the
cells identified by "X's". I~t will be noted that in this
embodiment, the positions o~ the plugged cells at the end
faces of the filter bod~ are not congruently spaced when
measured from the center o~ the central cell at each of
the end faces~ Similarl~, the openings 314 in each of
the reverse ~asks will not be congruently spaced between
the masks when measured with respect to their axial centers.
Two other embodiments are depicted with respect to
Figs. 23 and 24 and utilize a pair of identical masks
with a honeycomb structure having the axial centers of
its end faces in a thin wall between cells. The honey-
comb structure 310 may again be provided circular end
faces 312 and 313, the axial centers of which are located
in the center of or near the center of a thin wall 317-
in one embodiment at or near the mid point of a length
of wall between adjoining cells 316, as indicated by the
pOillt 330 in Fig. 23, and in another embodiment at or
near the intersection of a pair of thin walls, as
indicated by the point 331 at the intersection of the thin
walls numbered 317 and 332 in the same figure. A pair of
identical circular masks are used, again having openings
314 and protrusion locations 315 alternated in row~ and
columns as indicated in ~ig. 24 corresponding to the
rows and columns of cells o~ ~ig. 23. Their axial centers
lie, in the irst embodLment, bPtween an opening location
and an adjoining pro~rusion location as represented by the
point333 (when used with end ~aces centared at the point
330~, and, in the second embodimentl between four ad-
joining opening and protrusion locations as represented
~33~
by the point 334 (w-hen used wlth end ~aces centered at
point 331~, as depicted in ~ig. 24. A mask having its
axial center at th~ point333 when aligned on the end
faces 312 and 313 with that point o~er the point 330 will
lie in one o~ two orientations 180~ apar~. Each
orientation will expose a dif~erent subset of cells
indicated by the "X's'l and "O's", respectively, in Fig.
23. A mask having its axial center at the point 334
when aligned on an end face 312 or 313 with that point
over the point 331 will lie in one o~ four orientations
90 apart. Each orientation will again expose one of
the two subsets of cells indicated by the "X's" and "O's"
in Fig. 23, the subsets of cells exposed by adjoining
orientations (i.e. those separated by 90) being
different while those exposed by opposite orientations
(i.e. separate by 180~ being the same. In either case,
alignment of the mask and end face axial centers can again
be achieved by approximately centerin~ the mask against
the end face (i.e. positioning it with its axial c~nter
within an area centered about the axial center of the
end face and sufficiently small so that the mask will only
align with its axial center opposing that of the end face)
and vibrating it in~o alignment while its axial center
remains in that area. Again, this area will have a
~S diameter somewhat less than twice the magnitude of the
cell pitch, depending upon the tip diameters of the
protxusions, but may always be as great as one cell pitch
in magnitude regardless of the protrusion tip diameter.
It is envisioned that in some applications, it will
be found that the masks may be approximately centered in
selected initial angular orientations on the end face and
vibrated into alignment in a preselected relative angular
relationship. Alternatively9 the proper relative angular
orientation of the identical masks would be verified in
some automatic ~ashion to assure that when desired,
different subsets of cells are exposed at each of the
46
end aces in the honeyco~b structure for plugging. One
way would be to mark each mask in some ~ay, say at a p~int
on its periphery, so that the relative angular orientation
of the two masks can be compared by suitable sensing
equipment and circuitry to signal that desired relati~e
angular alignment is achieved. Another way would be to
optically ~iew either end face of a structure having a pair
of masks fitted or a structure having cells plugged at
one end face and a ~ask fitted to its remaining end face
to ascertain if light is passing through the structure
be~ween ~he end faces. Appropriately aligned ~asks should
allow no light to pass through the structure in the area
where cells are to be alternately plugged. An appropriate
signal can be generated to indicate proper alignment is
achieved and that the structure is ready for plugging or
that alig~ment was not achieved.
It is further envisioned that where elastic masks
are being automatically fitted to honeycomb structures, it
may be necessary to provide means to press the mask against
the end face to assure complete insertion of the elastic
protrusions.
Although the invention has been described with
respect to aligning circular masks to circular end faces
and square cell cross-sections, it is envisioned that the
invention may be successully employed with other end
~ace and cellular geometries. Other desirable end face
geometries may include oval and race-track configurations.
Cellular geometries can be circular, oval or any suitable
polygon shape, including triangle, hexagon, and any
quadralateral. A corral, if provided in such cases, may
be circular allowing 360 rotation of the body about the
surface. In such cases, the axial center of the mask and
end ~ace will lie at the center o thP smallest circular
area in which the body or end face may be axially rotated
360, typically the midpoint of the longest transverse
axis across the ~ask or end ace Ce.g. the diagonal o
3~
47
a s~uare or rectangular end ~ace). ~lternatively, a non-
circular corral may be used to lImit the range o~
angular motion o~ a noncircular mask so as to assure
alignment in a particular or one of a limited number
of angular orientations.
It is also envisioned that a corral, if provided,
need not be affixed to the honeycomb structure as
previously described, but may alternatively be affixed
to some other stationary object ox even affixed to -the
vibration source.
Moreover, it is envisioned that in some
applications lateral and/or angular alignment may he
assisted by the use of unusually sized and/or shaped
cells and protrusions provided at discrete locations
on the body and surface to more particularly limit the
lateral and/or angular orientation in which the body may
align on the surface.
It is also envisioned that means other than a
corral around the periphery of the mask (or honeycomb
structure~ may be used to limit the relative lateral and,
if desired, rotational motion between the body carrying
the protrusions in the honeycomb surface. For example,
a rigid member such as a pin or similar means may be
passed through and between a mask and an end face of a
2S honeycomb structure as fixing their relative lateral
positions during the vibrating step. In one embodiment
depicted in Fig. 25, a member 340 has been inserted
through an opening 341 at the axial center of a first
reverse mask 311. The mask 311 with member 340 is
positioned against an end face 312 of the structure 310
as indicated by the arrows 342 ~ith the member 340
extending into the central cell 329 of the end face 312
The mask 311 is then Yibrated into alignmentD In this
con~iguration, the mask 311 is ~ree to rotate but is
constrained in the lateral mo~ement of its axial center.
The member 340 may then be removed through ~he mask 311
~3~
48
and cement pressed through the opening 341 into the
proximal end of the central cell 329 during the plugging
step~ In a second em~odiment, a 501 id rod 343 or the
li~e may be passed khrou~h the length of a central cell
329 of a honeycomb structure, as indicated in ~igs. 26
and 26a. In ~ig. 26, the rod 343 extends ~rom the
central cell 32q at a first end ~ace 312 of the struc~ure
310. A first reverse mask 311 similar to that in Fig.
25 and having a similar opening 341 at its axial center
is positioned with the rod 343 through the opening 341
and vibrated into alignment. The structure 310 is then
inverted, as indicated in Fig. 26a, with the rod 343
protruding from the remaining end face 313 of the
structure 310. The remaining mask 311a of the pair of
reversed masks, which is also pro~ided with an opening
341a at its axial center, is placed over the rod 343
and against the end face 313 and vibrated into alignment.
The rod 343 is then removed ~rom the structure for
plugging of the alternate cells at its ~wo end faces 312
and 313 through the masks 311 and 311a. The opening 341
or 341a at the axial center of the one reverse mask 311
or 311a that corresponds to a protrusion location in the
plugging pattern of that mask is temporarily capped to
prevent the plugging of that end of the central cell
329. It is further envisioned that two or more rigid
me~bers 344, as depicted in Fig. 27, may be provided
between an end face 312 of a honeycomb structure 310 and
mask 311 to curtail relative rotational as well as
relative lateral movement between the mask 311 and the
end face 312. The members 344 may be inserted into any
two of the openings 345 of ~he mask and the members 344
inserted into the proper corresponding cells at the end
face 312. The pro~rusion 315 of the mask 311 may then be
vibrated into engagement.
Lastly, relative movement between a first body
~ember and a second honeycomb sur~ace member need not
:a2a~
49
be re~tricted by a means extending between the two members
but rather may be restricted by means, again such as a
pin, extending between one ~f the two me~bers and a ~ixed
o~ject. ~or example, a pin may be provided protruding
from the upstream face of the ~ask and the lateral motion
of the mask restricted by fixed means such as a tube fixed
in a frame which accepts and restricts the movement of the
pin protruding from the mask to the inner diameter of the
tube.
While fundamen~al novel features of the invention
have been shown and described with respect to a preferred
and other embodiments, it will be understood that various
omissions, substitutions and changes in the form and
details of the methods and apparatus heretofore described
may be made by those skilled in the art without departing
from the scope of the invention which is set forth in the
following claims.
